Trialing this as an alternative to CAS that is a little easier to
configure and can help us delegate authentication to other OIDC
services.
Change-Id: Iad63724d349334910af8fed0b148e4ba428f796b
Reviewed-on: https://cl.tvl.fyi/c/depot/+/4608
Tested-by: BuildkiteCI
Autosubmit: tazjin <mail@tazj.in>
Reviewed-by: lukegb <lukegb@tvl.fyi>
